A 4WD car is the choice preferred by many driving enthusiasts and off-road adventure seekers because these cars are designed to deliver performance even under the most trying conditions. They are the perfect companions for off-road driving as many of the parts are well-suited for rough roads and inclement weather conditions.

One such part that is sure to help a 4WD deliver on its performance is a Hilux diff drop. In this article, we are going to take a detailed look into how a Hilux diff drop works and why it is a necessary part of every 4WD. 

What Is A Hilux Diff Drop?

First off, it is important to understand that a Hilux diff drop is a modification or an accessory that enhances the performance of your vehicle. This means it automatically is not included in your vehicle and you have to add this to your car at a cost that includes the price of the product and the services of a mechanic if you can’t do it by yourself.

A Hilux diff drop is a bracket that helps to move the diff housing down so your CV joints are in better alignment. This helps to prevent CV angles from lifting the front of your 4WD when you drive through rough conditions. 

Now that you have a basic idea of what a Hilux diff drop does, let’s see how it works.

Working Of A Hilux diff drop

The main role of a Hilux diff drop is to reduce the possibility of breaking a CV joint. So, before we go on to understand how a Hilux diff drop works, let’s understand a bit about CV joints and the role they play in your car.

What is a CV joint?

In most cars, the engine is quite far away from the wheels that drive it. These two vital parts are connected through a complex maze of parts that includes shafts, gears, chains, and possibly even a transfer case. While this makes sense, the catch is that none of these parts are really the best choice to allow any movement. In other words, these parts can’t turn at corners as they are not designed for any movement. Rather, they are designed merely to keep the engine and the wheels connected.

So, now you need something that will turn the wheels after taking power from the engine. For many years this was achieved by two hinges that were connected at 90 degrees. While this worked great for small cars, it didn’t particularly give the maneuverability needed for larger cars. Also, they were not designed for sharp angles as this caused the hinges to rub against each other, thereby increases the chances of wear and tear.

Given these circumstances, car designers and manufacturers came up with the idea of using a Constant Velocity (CV) joint to address both the above concerns. This joint gave a smoother ride than before as the hinges didn’t have to rub against each other and it helped the car to make sharp turns quickly.

This was achieved by combining two joints called a Tripod and Rzeppa joint. Let’s not go into the technicalities here and it suffices to understand that these are ball bearings that fit into grooves to give them the flexibility to turn when needed. These bearings with matching grooves allow the angular movement needed to make sharp turns.

So, where does a Hilux diff drop come in here? 

Problems with a CV joint

Many times, the CV joint is not as efficient as it should be because of a ton of limitations. The biggest limitation of a CV joint is that it requires frequent lubrication and the most common way is to use moly grease with a rubber boot. Another problem is that there is always a possibility to push the joint way more than what it can handle and this causes the joints to get locked up. Further, when you have a wheel at full droop, it can cause binding issues while heavy loads can increase the effects of shock absorption and loading.

To sum it up, there are four possible problems with a CV joint and they are:

  • Requires lubrication often
  • Locking up of joints
  • Binding issues
  • Shock loading

Role of a Hilux Diff Drop

A Hilux diff drop addresses many of the problems that come with a CV joint. It modifies the mounting point of the diff and as a result, lowers it down from the chassis. This reduces the angle of operations and hence, there is a lot less pressure on the CV joints. This way, it addresses the limitations that come with the use of a CV joint by reducing the lubrication it needs, the possibility of a lockup, and the binding and loading issues that come with heavy loads. 

Since the CV joints are not used so much, most of the negative impacts are countered with the help of a Hilux diff drop and this is what makes it so indispensable for today’s 4WD.

Now, this brings up an interesting question. How much should you drop to bring down the impact of off-road driving on a CV joint? Ideally, if you’ve lifted your IFS 4WD about three to four inches off the ground, you should consider dropping the diff. But this is not written in stone and depends to a large extent on how much you’ve lifted and the type of car, make, and model. Nevertheless, it is important to note that a Hilux diff drop can go a long way in reducing the pressure on your CV joints and the resultant problems that may come with it.

To conclude, a Hilux diff drop is an essential accessory for many 4WD cars, especially if you plan to use them for off-roading driving adventures or even for competitive sports. The many sharp turns require the presence of a CV joint that can handle only a certain load and angle. To ease the pressure on these joints, you need a Hilux diff drop, a bracket that’s used to bring the diff housing down.